Fusible electric switch equipped with combination fuse holder and arcing contact



July 5, 1966 Filed Jan. 11, 1965 L. BAIRD ETAL 3,259,718 FUSIBLE ELECTRIC SWITCH EQUIPPED WITH COMBINATION FUSE HOLDER AND ARCING CONTACT 5 Sheets-Sheet l INVENTORS. LESL/E L. 6/! m0,

CLARE/V055. GEHR/ /GE /TQ.

ATTORNEY y 1966 L. L. BAIRD ETAL 3,259,718

FUSIBLE ELECTRIC SWITCH EQUIPPED WITH COMBINATION FUSE HOLDER AND ARCING CONTACT Filed Jan. 11, 1965 5 Sheets-Sheet 2 IN VENTORS. LEJL/E L. BA mo,

CLARE/V055. GEHRl/VGf/LJ/T.

ATTORNEY July 5, 1966 L. BAIRD ETAL 3,259,713

FUSIBLE ELECTRIC SWITCH EQUIPPED WITH COMBINATION FUSE HOLDER AND ARCING CONTACT Filed Jan. 11. 1965 5 Sheets-Sheet a uvvz-rxvroas: 4554/5 LEA/R0, CLARENCE 5,, Own/Ma gy ATTORNEY July 5, 1966 L. BAIRD ETAL 3,259,

' FUSIBLE ELECTRIC SWITCH EQUIPPED WITH COMBINATION FUSE HOLDER AND ARCING CONTACT 5 Sheets-Sheet 4 Filed Jan. 11, 1965 ATTORNEY y 66 L. BAIRD ETAL 3,

FUSIBLE ELECTRIC SWITCH EQUIPPED WITH COMBINATION FUSE HOLDER AND ARCING CONTACT Filed Jan. 11, 1965 5 Sheets-Sheet 5 BY M A TTORNE) United States Patent FUSIBLE ELECTRIC SWITCH EQUIPPED WITH COMBINATION FUSE HOLDER AND ARC- ING CONTACT Leslie L. Baird, Swarthmore, Pa., and Clarence B. Gehringer, Jr., Audubon, N.J., assignors to General Electric Company, a corporation of New York Filed Jan. 11, 1965, Ser. No. 424,731 6 Claims. (Cl. 200-114) This invention relates to electric switches, and more particularly it relates to a switch in which contact means for switching an electric current circuit and fuse means for protecting the circuit are integrally combined.

The present invention has special utility in relatively high current (e.g. 1,200 amperes), 600-volt service entrance applications where multipole fused switches with bolted-pressure contacts are commonly used to switch and to protect A.-G. electric power circuits and loads fed from service entrance conductors. In practice such devices are equipped with low-cost manually or electrically operated mechanisms for opening the main switch contacts when desired, thereby breaking the circuit in which the device is connected and interrupting whatever load current may then be flowing. Overload and fault protection is automatically provided by the electric fuses which are designed to blow under overcur-rent conditions with a time delay inversely-related to overcurrent magnitude. By using Class L (NEMA standards designation) lowvoltage current-limiting cartridge fuses, current as high as 200,000 amperes can be quickly and safely interrupted in the event that a very severe fault or short circuit occurs.

Sometimes an overload or fault condition will pie-exist in the protected circuit when a service entrance switch is being closed. On realizing this, an operator is likely to react by immediately attempting to reopen the switch. If the fault current magnitude is sufficiently high, the fuses will interrupt it with dispatch before the operator can separate the main contacts of the switch. But for complete protection, the separable contacts of a service entrance switch should be designed to safely interrupt the maximum amount of current (e.g. 6 times rated full-load current, or 7,200 amperes) that the fuses will let through, without blowing, for the minimum length of time required to carry out a switch opening operation.

In some fusible switch designs, provisions are made for mounting removable cartridge fuses in place of the movable blades of the switch. In order to minimize heat generation and cumulative power losses in a multipole high-current switch of this design, it is desirable to be able to establish high-pressure direct connections between the respective terminals of the fuses and the cooperating stationary contacts of the switch. Thus one of the terminals of each fuse is employed as a movable main contact of the switch, and it is important that the contact surfaces of this terminal always remain clean and smooth. Since an electric arc may be drawn upon separation of the switch contacts, and since an arc tends to erode or pit any surface that it touches, each fuse terminal that serves as a circuit making and breaking contact of the switch must be protected by appropriate arcing contact means from exposure to arcs.

Accordingly, a general object of the present invention is the provision of an improved combination fuse terminal holder and arcing contact for fusible switches.

A more specific object of our invention is to provide a fusible switch having a novel fuse holder that facilitates removal and replacement of the fuse.

Another object is to provide a fusible switch having a novel fuse terminal holder that facilitates arc interruption while shielding the fuse terminal from adverse arc effects.

ice

In carrying out our invention in one form, a deadfront, high-current fusible switch is provided with a pivotally movable switch member adapted to support one or more removable cartridge fuses. The switch member is disposed for movement between a predetermined closed position, in which the upper and the lower terminals of the supported fuse will respectively engage an associated pair of spaced-apart, relatively stationary main contacts of the switch, and a predetermined open position in which the upper fuse terminal will be separated from the corresponding stationary main contact. A relatively stationary arcing contact is .connected electrically to said corresponding main contact and is disposed physically adjacent thereto, and an arc chute may be disposed above this arcing contact if desired. The upper terminal of the fuse is rel-easably held by a cooperating arcing contact that is pivotally mounted on and normally fastened to the movable switch member.

So long as the pivotally mounted arcing contact is fastened in a predetermined normal position on the switch member, a first surface thereof will separately engage the aforesaid stationary arcing contact during movement of the switch member from its closed position toward its open position until after the upper fuse terminal separates from the corresponding main contact, and another surface thereof continuously engages the side of the upper terminal nearest the main contact after said contact separation. Suitable means is provided for maintaining good contact pressure between the last-mentioned surface of the pivotally mounted arcing contact and the side of the upper fuse terminal engaged thereby, and means is also provided for unfastemng this contact which is then pivotable from its normal position to release the support fuse for convenient removal from the switch member. With this arrangement, any are that exists during a switch opening operation will be drawn between the first surface of the pivotally mounted arcing contact and the relatively stationary arcing contact, and it will be safely directed upwardly and away from all contact areas of the upper terminal of the fuse.

Our invention will be better understood and its various objects and advantages will be more fully appreciated from the following description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a side elevation of a fusible electric switch embodying our invention, with portions of the front and the back frames of the switch broken away to more clearly show its interior parts;

FIG. 2 is a partial front elevation of the switch shown in FIG. 1 after the front frame and its associated parts as well as the arc quench-ing means have been removed.

FIG. 3 is an enlarged side view of the cartridge fuse shown in FIG. 1 and of the means by which it is removably supported according to our invention;

FIG. 4 is an enlarged sectional view taken through lines 44 of FIG. 3;

FIG. 5 is a side elevational similar to FIG. 1 but witlrthe movable switch member shown in its closed p0s1t1on;

FIG. 6 is a partial side View of the switch during a switch opening operation; and

FIG. 7 is a side elevation of the switch shOWn in FIG. 1 with the front frame and associated switch elements tilted to a disconnected position.

Referring to FIG. 1, the illustrated switch will be seen to include a stationary unit 11, at least one pair of spaced-apart incoming and outgoing electric current conductors 30 and 40 fixedly supported by the unit 11, and a carriage 101 adapted to support means for closing and opening a circuit between the separate conductors 30 and 40. The carriage 101 also contains a mechanism for actuating the circuit closing and opening means, and this mechanism includes a manual operating handle 120 that is accessible from the front side of the carriage escutcheon 110. The handle 120' is pivotally movable between a vertical, switch open position shown in FIG. 1 and a raised, switch closed position shown in broken lines in FIG. 5.

The construction of the stationary unit 11 of the switch will now be described. The unit includes a back frame having generally L-shape metal side structures that are rigidly fastened together by a plurality of cross pieces. As is best seen in FIG. 7, each of the side structures comprises an angle disposed vertically to form a rear corner post 12 and bent horizontally to form a side member 13 extending frontwardly from the lower end of the post 12. At the front end of the member 13 a relatively short upstanding plate 14 is affixed, and this plate is additionally fastened to the midsection of the post 12 by means of a diagonal brace 15. A notch 16, bounded by a horizontal upper lip 14a and a vertical lower lip 14b, is provided in the frontside of the plate 14 for removably receiving and holding a support pin 116 of the carriage 101.

' At the point 17 on the rear section of the side member 13 there is pivotally mounted an upstanding support and locking member 18. This member is spring biased to a position in which a corner 18a thereof bottoms on the horizontal flange of the side member 13 and in which an anchor pin 18b carried by the member 18 is disposed directly above the corner 18a as shown. The side member 13 is joined to the corresponding member on the far side of the stationary unit by a bar that extends across the bottom of the unit, and the two corner posts 12 are spanned at different elevations by two horizontal channels 20 and 21 that are tightly bolted to the backsides thereof. The channels 20 and 21 are made of rigid, electrical insulating material.

The stationary unit 11 also includes at least one pair of spaced-apart relatively stationary electric contacts '31 and 41 which are mounted on the insulating channels 20- and 21 of the frame described above. A front view of the one pair of contacts is shown in FIG. 2, and other similar pairs can be disposed in side-by-side relation thereto. It will be seen in FIG. 2 that the contacts 31 and 41 are of jaw-like design, that is, each one comprises a pair of electrically interconnected, physically spaced electroconductive elements or contacts 32 and 33 arranged to grip opposite sides of a movable bladelike contact inserted in the gap therebetween. The contacts 32 and 33 preferably comprises defiectable silver plated copper bars having their flat sides in parallel vertical planes that are perpendicular to the channels 21 and 22 and having their forward edges beveled to guide the cooperating blade on its insertion therein.

Adjoining the outer side of the bar 32 of the lower stationary contact 41 is a dished member 34 that is rigidly fastened to the associated channel 21. The bar 32 is aflixed to this member. A depending portion of the bar 32 is connected to and supports the aforesaid conductor 40 in a convenient disposition for connection to an external electric power circuit, and a similar portion of the companion bar 33 is also attached to the conductor 40. The bars 32 and 33 extend vertically from the conductor 40 in spaced parallel relation to each other, and another dished member 37 is located on the outer side of bar 33 opposite the member 34 as shown. At one point between the bars 32 and 33 a suitable spacer 38 is disposed for the purpose of maintaining between the inner sides of the bars at this point a predetermined minimum gap whose length is approximately the same as the thickness of the blade to be inserted.

In order to ensure a tight yet separable connection between :the bars 32 and 33 and the blade that is inserted therebetween, suitable pressure applying clamping means is provided. As shown in the drawings this clamping means includes a common rotatable drive shaft 60 extending horizontally through aligned apertures in the respective bars 32, 33 and members 34, 37 that comprise the lower contact 41. The shaft 60 is insulated and is surrounded at the contact 41 by a pair of annular members 62 and 63.

The annular member 63 is housed in the dished member 37, and preferably it comprises a non rotatable unit having an internal screw thread. The other member 62 preferably comprises an externally threaded tubular bolt that can be rotated with respect to the nut 63 by predetermined rotation of the shaft 60. The bolt head is located in the dished member 34, and the bolt extends along the shaft 60' into the member 37 where it mates with the nut 63. Thus the head of the bolt 62 and the nut 63 respectively bear against opposite sides of the stationary jaw-like contacts, and the cooperating blade-like contact can be tightly clamped between the bars 32 and 33 by rotating the shaft 60 so as to turn the bolt into the nut. This bolted pressure arrangement will be further described hereinafter.

The construction of the illustrated upper contact 31 of the stationary unit 11 is similar to that described above for the lower contact 41. However, the spaced bars 32 and 33 forming the jaw-like contact 31 extend upwardly instead of downwardly from the associated members 34 and 37 to the attached conductor 30, with the member 34 being rigidly fastened (by the means shown at 39 in FIG. 1) to the upper insulating channel 20 instead of to the lower one.

It is now apparent that by electrically interconnecting the paired contacts 31 and 41, a closed electric circuit will be formed between corresponding upper and lower conductors 30 and 40, and for this purpose a bridge-like electroconductive element 201 having blade-like main contacts 201a and 201b at opposite ends thereof is provided. The element 201, which is shown in phantom in FIG. 2, preferably comprises a cartridge fuse having vertically oriented blade-like tangs or terminals that serve as the main contacts referred to. This fuse is removably supported in a manner hereinafter fully described by a movable switch member on the aforesaid carriage 101. When its terminals 201a and 201b are inserted between the jawlike contacts 32-33 of 31 and 41, the fuse 201 completes a main current path between conductors 30 and 40. Highpressure, low-resistance connections between these cooperating fuse terminals and stationary main contacts is then obtained by actuating the above-described clamping means.

The common drive shaft 60 of the clamping means associated with the upper contact 31 and the corresponding drive shaft 60 below have been interconnected for joint rotation by -a pair of tie bars 64, only one of which is shown in FIG. 2. The upper ends of the tie bars 64 are pivotally attached at 65a to a pair of cranks 65 that are respectively keyed to opposite ends of the upper shaft; the lower ends of these bars are pivotally attached at 66a to a pair of cranks 66 keyed to opposite ends of the lower shaft. Both of the shafts 60 are biased in a pressure relieving direction (counter clockwise as viewed in FIG. 1) by spring means 67 connected in tension between the tie bar 64 and the adjacent corner post 12 of the stationary unit so as to urge the bar upwardly. Both shafts are simultaneously rotated in the opposite, pressure-applying direction by actuating means located on the carriage 101, soon to be described.

The upper relatively stationary contact 31 also includes a pair of jaw-like arcing contacts 42 and 43. These areing contacts comprise elongated, relatively thin metal members disposed between the bars 32 and 33 adjacent to the main contact area thereof. The upper ends of the members 42 and 43 are physically and electrically connected to the stationary bar 32 by a bolt 44 or other suitable means. The lower portions of the members 42 and 43 are bent to protrude in front of the bar 32 (best seen in FIG. 5), where they form a relatively short gap in alignment with the gap between the bars 32 and 33 (best seen in FIG. 2). The tips 42a and 43a of the protruding portions of these members are turned up to form are runners.

The protruding portions of the relatively stationary arcing contacts 42 and 43 are arranged to be separably engaged by a blade-like arcing contact 202 that is mounted on the movable switch member of the carriage 101 in association with the main contact or terminal 201a of the cartridge fuse 201. When the fuse 201 is in a closed circuit position (FIG. 5 its associated arcing contact 202 is disposed between the cooperating arcing contacts 42 and 43 which yieldably grip opposite sides of the contact 202 to maintain a good electrical connection therewith. During movement of the fuse 201 toward an open circuit position, the arcing contacts 202 and 42, 43 will not separate until after the fuse terminal 201a and the main contact elements 32, 33 are disengaged, whereupon an electric arc may be drawn between the arcing contacts. Any such are will be contained and extinguished Within an electric arc chute 50 that embraces the protruding portions of the stationary arcing contacts 42 and 43.

As is indicated in FIG. 1, a clamp 51 and a pair of long bolts 52 are used for removably securing the arc chute 50 to the stationary unit 11 in association with contact 31. The bolts 52 are anchored in insulating material 53 that in turn is rigidly fastened to the front side of the stationary contact member 34. Since neither the presence of the are chute 50, its design particulars, nor the method of mounting it on the stationary unit 11 are material to the present invention, a detailed description of these parts will be omitted.

The construction of the carriage 101 of the switch will now be described. It comprises a metal front frame having generally L-shape side structures that are rigidly fastened together by a plurality of cross pieces. Each of the side structures of this frame comprises an angle forming a vertical front corner post 102, a side plate 103 affixed to the post 102 near its lower end and extending rearwardly therefrom, and a diagonal brace 104 interconnecting the rear of plate 103 and the upper end of post 102. A shaft 105 extends horizontally across the bottom of the carriage and is journalled at its opposite ends to the respective side plates 103, and two rigid cross members 106 and 107 span thecorner posts 102 to complete the frame. The escutcheon 110 is bolted at 111 to the cross members 106 and 107 of the front. frame as shown. This frame, in combination with a switch member 203 that is movably supported thereby and a mechanism for moving the same, comprises a portable unit that is separably hinged to the stationary unit 11 for angular movement between two different positions.

For the purpose of separably hinging the portable unit on the stationary unit, a coaxial pair of lateral-1y projecting support pins 116 are respectively located on the opposite side plates 103 of the carriage 101 in the vicinity of the front side thereof. These pins fit into the aforesaid notches 16 in the upstanding plates 14 of the stationary frame, and the carriage 101 can pivot or swing about the common axis of these pins to and away from a predetermined first or operating position in which it is shown in FIGS. 1 and 5. This position is determined by the anchor pin 18b abutting the top edge of a slot 118 formed in the bottom of each side plate 103 of the carriage as shown. So long as the carriage 101 is in the operating position, the upper lip 14a of each notch 16 overhangs another pin 117 located next to each support pin 116 (see FIG. 1) to prevent lifting the portable unit vertically with respect to the tationary unit 11.

From its first position the portable unit can be pivoted on its support pins 116 through an angle of about 75 or 8.0 degrees to a second or tilted position shown in FIG. 7, which position is determined by an appendage 102a on each of the corner posts 102 abutting the under side of a stop pin 15a that is atfixed to each of the diagonal braces 15 of the stationary unit. From its tilted position the portable unit can be separated from the stationary unit for installation and servicing convenience by manually lifting it so that the pins 116 leave the notches 16, for which purpose a C-shaped carrying handle 108 is prominently located on the upper cross member 106 of the carriage 101.

The portable unit includes the switch member 203 which is adapted to support at least one cartridge fuse 201. The switch member 203 is pivotally mounted on the side plates 103 of the carriage 101 for reciprocal movement relative there-to between predetermined closed and open posit-ions. The switch member is a channel of rigid insulating material extending horizontally across the carriage between a pair of attached metal brackets or legs 204 that are supported by a coaxial pair of pivot pins 119 projecting laterally from the respective side plates 103 in the vicinity of the back side of the carriage. With the portable unit in its aforesaid first position, the pivot pins 119 are about coaxial with the lower rota-table shaft 60 of the previously described contact clamping means. The axes of the pivot pins 119, the support pins 116, and the shaft 105 are all oriented parallel to each other.

More than one cartridge fuse 201 can be removably supported by the switch member in side-by-side electrically insulated relation to each other, each fuse being located adjacent to the back side of the carriage with its terminals aligned with a corresponding pair of the relatively stationary jaw-like contacts 31 and 41. For each fuse supported, the member 203 is provided with a pair of fuse holders 205 and 206 arranged to hold the opposite terminals 201a and 201k of that fuse. The construction of these fuse terminal holders is best seen in FIGS. 3 and 4.

The lower fuse terminal holder 206 is in the form of a generally rectangular collar 206a projecting rearwardly from the bottom of the switch member 203, to which it is afiixed, and a relatively thin U-shape bracket 20612 subtending the collar. The blade-like fuse terminal 201b is loosely embraced by the collar 206a, which restricts lateral movement of the blade, and it is supported by the interior surfaces of the bracket 20% which limit edgewise movement thereof. The bracket 206k is made thinner than the blade 201!) so as to avoid interfering with the direct electrical connection between the blade and the jaw-like contact 41. The hook-like protrusion 2060 shown at the bottom of the holder 206 will extend behind a tubular bolt 62 on the lower rotatable drive shaft 60 of the contact clamping means whenever the portable carriage 101 is in its aforesaid operating position.

In accordance with our invention, the upper fuse terminal holder 205 is in the form of an inverted L-shape metal member that comprises the aforesaid arcing con-. tact 202. This contact has one end 202a pivotally mounted on an upright bracket 207 that is affixed to the top of the switch member 203, and its other end is integrally connected to a pair of parallel, spaced-apart arms 205a. As is best seen in FIG. 4, a threaded bolt 208 attached to the free end of each of the arms 205a is nor-. mally secured in a cooperating nut 209 aflixed to the switch member 203, thereby releasably fastening the con tact 202 to the switch member. The hexagonal head of each bolt 208 may be slotted to allow turning by a screw driver. The arms 205a loosely embrace the blade-like fuse terminal 201a to accommodate limited lateral movement thereof for alignment purposes as the blade enters the main contact jaws 32 and 33 of the upper stationary contact 31 during a switch closing operation. The arcing contact 202 is made thinner than the blade 201a so as to avoid interfering with a direct electrical connection between the blade and the contact 31.

The horizontal arms 205a of the fuse terminal holder are adjqined by a vertical side 2021:. of the contact 202.

7 A surface of the contact side 20217 is adapted to abut the leading edge of the fuse terminal 201a as shown, and contact pressure is there maintained by a spring-loaded plunger 210 that urges the terminal away from the switch member 203. By leading edge we mean the side of the fuse terminal 201a that is nearest to the stationary contact 31 with the switch member 203 in its open position (FIG. 1). Because only this side of the fuse terminal is engaged by the contact 202, any electric are attaching to the arcing contact during a switch opening operation will immediately move in an upward direction, thereby minimizing contamination of the main contact surfaces of the terminal 201a by the are products. For yieldably holding the fuse terminal 201a against the arcing contact side 202b, whereby good electrical and physical contact is maintained therebetween, the plunger 210 has been provided with acoaxial helical spring 211 (best seen in FIG. 4) that is captured in compression between a washer 210a on the plunger and an insulating grommet 212 through which the front end of the plunger extends. The grommet 212 is located in a hole in a bracket 213 depending from the top of the switch member 203 to which it is attached.

By unfastening the arms 205a from the switch member 203, the upper fuse terminal holder 205 can be bodily pivoted about 202a from a normal position (shown in solid lines in FIG. 3) to another position (shown in broken lines) wherein the arcing contact 202 is disengaged from the fuse terminal 201a. The fuse 201 is now released from the switch member 203 for removal and replacement purposes, while the fuse terminal holder remains attached to the switch member. This operation is most conveniently accomplished while the carriage 101 is in its tilted position described hereinbefore. At the same time the combination arcing contact and fuse holder, if worn or damaged, could itself be removed for replacement purposes by simply removing the cotter pin 214 that keeps the pivot pin for this unitary combination attached to the bracket 207.

The pivotal fuse-holder-arcing-contact combination of our invention can alternatively be used to hold other bridge-like electrical apparatus. For non-fused, boltedpressure isolating switch applications or the like, a plain bar of copper could be substituted for the cartridge fuse illustrated and described herein.

The switch member 203 of the portable unit is moved between its open and closed positions by an operating mechanism that will next be described. The operating mechanism in its preferred form includes the manual operating handle 120. As can be seen in FIG. I, handle 120 depends radially from the front end of a short horizontal shaft 121 -to which it is affixed. The shaft 121 extends through the escutcheon 110 and is journaled near its rear end in a bearing 122 that is centrally supported by the upper cross member 106 of the carriage 101. A plate-like crank 123 is keyed to the rear end of the shaft 121.

The plate 123 is drivingly connected to the rotatable shaft 105 of the switch operating mechanism by means of a tie rod 124. A pin 123a protruding rearwardly from the plate 123 is loosely embraced by an eyelet formed at the upper end of the tie rod 124. The lower end of this rod is pivotally attached to a pin 125a spanning a yoke 125 that is pivotally supported at the distal end of an arm 126 projecting radially from a central portion of the shaft 105 to which it is rigidly anchored, whereby a universal joint is formed between the tie rod 124 and the arm 126. With this arrangement, the shaft 105 is rotated approximately 45 degrees in a clockwise direction (as viewed from the right side of the switch) in response to the operating handle 120 being pivoted counterclockwise (front view) about the axis of the shaft 121 from its vertical position shown in FIG. 1 through an angle of approximately 135 degrees to its fully raised position. If desired, the shaft 105 could alternatively be driven by other suitable means, such as a stored energy spring-actuated mechanism.

It is desirable to releasably lock the manual operating handle 120 in each of its vertical and raised positions, for which purpose a spring loaded plunger 112 is mounted on the upper cross member 106 behind the escutcheon 110. Whenever the handle is in its vertical (open) position, which position is defined by a first shoulder 123b of the plate 123 engaging a boss 106a on the cross member 106, the plunger 112 is spring-biased rearwardly into a cooperating notch provided in the edge of plate 123, whereby counterclockwise movement of the plate is blocked until the plunger is withdrawn by pulling a knob 113 that is attached thereto. The knob 113 is accessible from the front side of the escutcheon 110. When the knob is pulled and counterclockwise movement of the which position is defined by an opposing shoulder 123d 7 of the plate 123 engaging the same boss 10611, the first shoulder 123k will move just beyond the plunger 112 which is then free to move rearwardly into a blocking position therewith, whereby reverse movement of the handle 120 in a clockwise direction is physically prevented until plate 123 is again released by manually pulling the knob 113.

The driven shaft 105, as was mentioned hereinbefore, extends horizontally across the carriage 101 and is journaled at its opposite ends to the respective side plates 103. A pair of cam members 127 are keyed to the shaft near its respective end. The preferred configuration of each cam member 127 is best seen in FIG. 1. provided with a cam slot 128 having a generally vertical section 128a that intersects and extends downwardly from the rear end of a generally horizontal section 1281). A roller 204a is disposed in the cam slot 128. The roller 204a is mounted on the supporting leg 204 of the movable switch member 203, and it traverses the cam slot 128 during closing and opening operations of the switch operating mechanism.

The action of the mechanism during a closing operation will now be considered.

The switch closing operation is accomplished in two distinct steps. The first step is carried out by releasing and angularly moving the manual operating handle through about one-half of its -degree counterclockwise closing stroke. This will cause the arm 126 on the shaft 105 to move through approximately three-fifths of its 45-degree throw, thereby rotating the shaft 105 and its cam members 127 a corresponding amount. During this step the front edge of the first section 128a of the cam slot 128 moves rearwardly and cams the roller 204a upwardly with respect thereto. As a result, the rollers 204a, the legs 204, and hence the switch member 203 are driven clockwise on the pivot pins 119 along an approximately 42-degree arcuate course from the initial open position shown in FIG. 1 to the closed position in which these parts are shown in FIG. 5. This clockwise movement of the switch member 203 carries the blade-like upper terminal 201a of the cartridge fuses 201 into wiping engagement with the associated jaw-like stationary contacts 31.

For the remainder of the closing operation, the roller 204a will be in the second cam slot section 12% whose bottom edge closely conforms to the arc of a circle concentric With the shaft 105, whereby the movable switch member203 is held in its closed position but no further clockwise angular motion is imparted thereto.

With the fuse-carrying switch member 203 in its closed position, and with the carriage 101 fixed in its operating position shown in FIG. 5, the terminals at the opposite ends of the cartridge fuse 201 directly engage both of the main stationary contacts 31 and 41 that are associated therewith, thereby making or completing a fused electric circuit between corresponding upper and lower conduc Each is tors 30 and 40. For the purpose of positively anchoring the portable carriage 101 in its aforesaid disposition to the stationary unit 11 while the switch is being closed, each cam member 127 has been provided with a lobe 127a Whose leading edge engages a roller 18c mounted on the adjacent support and locking member 18 so as to tilt this member counterclockwise upon initial clockwise rotation of the cam member 127. When so tilted, the anchor pin 18b carried by the member 18 shifts frontwardly from the mouth to an interior portion of the notch 118 that is formed in the bottom edge of the side plate 103 of the carriage 101. The carriage 101 is then locked to the stationary unit 11, and it cannot be moved relative thereto until the side plate 103 is subsequently released by egress of the pin 18b from the notch 118 when the cam member 127 returns to its original position. This prevents the hazardous possibility of opening the switch contacts by tilting the carriage.

The second step of the switch closing operation is used to actuate the above-described contact clamping means so as to apply high contact pressure on the then interengaging main contacts of the switch. This step is carried out by continuing to move the manual operating handle 120 through the remainder of its counterclockwise closing stroke to its fully raised position, thereby causing the shaft 105 and its cam members 127 to turn clockwise from the position shown in FIG. 5. If desired, spring means (not shown) could be coupled to the handle 120 so as to assist the operator in moving the handle during this part of its closing stroke.

With the cam member 127 in its FIG. position, a camming surface 129 on the rear edge thereof engages a roller 260 mounted at one end of a coupling lever 261 whose opposite end 262 is slotted. The .axle'of the roller 2'60 protrudes a short distance in the direction of the lower stationary contact 41 which is adjacent thereto. At a point midway between the roller 260 and the slot 262, the lever 261 is journaled on the pivot pin 119 which projects laterally from the side plate 103 of the carriage 101. A tension spring 263 (see FIG. 1) biases this lever in a counterclockwise sense to a normal position determined by a boss on the lever engaging the side plate 103.

With the lever 261 in its normal position and with the carriage 101 anchored in the fixed disposition shown in FIG. 5, the slot 262 will register with a pin 66b protruding from the crank 66 that is keyed to the adjacent end of the lower rotatable shaft 60' as previously described. (The lower shaft 60 is coaxial with the pivot pin 119.) The crank 66 is also provided with a slot 660 diametrically opposite the pin 66!), which slot registers with the protruding axle of the roller 260. Thus the crank 66 is coupled to the lever 261 for joint rotation therewith. The same coupling is provided at the far side of the switch.

As the second step of the switch closing operation is carried out, the camming edge 129 of the member 127 advances in such a manner as to drive the roller 260 and hence the lever 261 clockwise about the pivot pin 119 through an angle of approximately 45 degrees. The crank 66, being coupled to the lever 261, is correspondingly rotated with respect to the axis of the lower shaft 60, and the interconnected upper crank 65 is rotated conjointly therewith. As a result, each of the upper and lower drive shafts 60 of the contact clamping means is turned clockwise about its axis from the initial angular position in which it is shown in FIGS. 1, 3, and 5 to a predetermined tinal angular position spaced from the initial position by approximately 45 degrees. this turning each tubular bolt 62 is screwed into the associated nut 63, thereby reducing the spacing between the bolt head and the nut and compressing the interposed contact members 32, 33 and 201a (or 2011)). This contact clamping action is more fully explained above in connection with the description of FIG. 2.

The second step of the switch closing operation is completed when the manual operating handle 120 reaches its During the course of I 10 fully raised position (shown in broken lines in FIG. 5) where it is retained by the releasable locking means M2, 113 previously described. Brief consideration will now be given to a switch opening operation, which is essentiallythe reverse of the closing operation just described.

The switch opening operation is begun by releasing the operating handle 120 and angularly moving it in a clockwise direction (front view), thereby causing counterclockwise rotation (as viewed in FIGS) of the shaft and its cam members 127; The illustrated cam member 127 is provided with a hook-like part opposing the camming' edge 129, and a camming edge 129a on this part pulls the roller 260' and hence the lever 261 and the crank 66 in a counterclockwise direction. This action, which is aided by the springs 67 and 263, simultaneously turns both of the drive shafts 60' of the contact clamping means in a counterclockwise, pressure relieving direction. As the rear end of the second cam slot section 12% in the member 127 approaches the roller 204a, the coupling lever 261 returns to its normal position shown in FIG. 5 and each drive shaft '60 is returned to its initial angular position, whereby the bolted-pressure connections between stationary contacts S1, 41 and fuse terminals 201a, 20|1b are loosened before the movable switch member 203 is moved away from its closed position.

Continued clockwise rotation of the cam member 127 after the rear edge of its first cam slot section 128a makes contact with the roller 204a will cam the roller downwardly with respect .thereto. As a result, the switch member 203 and supporting legs 204 are moved counterclockwise on the pivot pins 119 along their predetermined arcuate course from closed to open positions. As is indicated in FIG. 6', this reverse movement of the switch member 203 will effect separation of the upper fuse terminal 20111 from the cooperating main contacts 32 and 33 before the cooperating arcing contacts 202 and 42, 43 have separated. Subsequently the arcing contacts are separated, whereupon an electric arc may be drawn between these parts. In accordance with our invention, the only path in the arcing contact 202 for continuing current comprises the vertical side 20 2b of this contact, and consequently a sharp bend is formed in the are as it loops upwardly away from the area of the fuse terminal 201a. This sharp bend expedites movement of the arc along the stationary arc runners 42a, 43a and in the arc chute where it is quickly extinguished, thereby opening the electric circuit between the corresponding upper and lower conductors 30' and '40 of the switch.

The switch opening operation is completed when the manual operating handle 120 reaches a vertical position (FIG. 1) Where it is again retained by the releasable locking means 112, 113.

As the movable switch member 203 is returning to its open posit-ion near the end of the switch-opening operation, the lobe 127a on the cam member 127 moves beyond the roller 18s on the support and locking member 18, and the rear edge of the lobe will engage and move a laterallyprotruding pin |18d on the member 118. This tilts the whole member 18 clockwise to a position in which the anchor pin 18b registers with the mouth of the notch 118 in the side plate 103' of the carriage !101, thereby disabling the anchoring means and releasing the carriage 101 for angular movement on its support pins 116 from the operating position shown in-FIG. 1 to the tilted position mentioned hereinbefore.

'In FIG. 7 the portable unit of the opened switch is shown after having been moved, relative to the stationary unit 11, to its tilted position. Such movement is effected simply by pulling manually the carrying handle 108 of the carriage 101 until the carriage is propelled by its own weight counterclockwise about the axis of its support pins 116. It will be apparent that during this swinging movement of the carriage 101 the axle of roller 260 and the slot 262 at opposite ends of each coupling lever 261 separate, respectively, from the diametrically opposed 1 1 slot 660 and pin 66b of the associated crank 66. The tilted position of the carriage 101 is reached when the appendage 102a on each of the front corner posts 102 of the carriage frame engages the under side of the cooperating stop pin 15a on each diagonal brace 15 of the stationary unit 11.

The support pins 116 are so located that the abovedescribed movement of the carriage 101 carries the lower fuse terminal 2011: out of engagement with the stationary contact 41, whereby the cartridge fuse 201 is completely separated from the associated stationary contacts 31 and 41 of the switch. In the tilted position of the carriage 101, as is best seen in FIG. 7, the fuse has both of its terminals disconnected and deenergized, and it is exposed for'safe and convenient removal from the fuse terminal holders 205 and 206. An operator can easily replace a blown fuse without danger of touching an energized (live) stationary contact of the switch. To improve accessibility and hence to expedite the unfastening and disengagement of the upper fuse terminal holder 205, the fuse-supporting switch member can first be moved, relative to the carriage 101, in a clockwise direction on the pivot pins 119 to its closed position by turning the manual operating handle 120 through its closing stroke. In order to ensure that the portable carriage 101 cannot then be moved from its tilted position to its operating position (FIG. 5), each cam member 127 has been provided with a boss 12711 that will not pass a laterally- -displaced edge b of the stationary diagonal brace 15 until the cam member 127 is returned to its original angular position by completing the opening stroke of the handle 120.

While a preferred form of our invention has now been shown and described by way of illustration, many modifications will occur to those skilled in the art. The claims which conclude this specification are therefore intended to cover all such modifications as fall within the true spirit and-scope of the invention.

What we claim as new and desire to secure by Letters Patent of the United States is:

1. A switch comprising:

(a) first and second contacts;

(b) a relatively stationary arcing contact connected electrically to the first main contact and disposed physically adjacent thereto; and

(0) means adapted removably to support a cartridge fuse having first and second terminals at opposite ends thereof, said means being movable between a predetermined closed positionin which the first and second terminals of the supported fuse respectively engage said first and second main contacts and an open position in which said first terminal and said first main contact are disengaged;

((1) said supporting means including means adapted to hold the first terminal of said fuse, said holding means comprising (i) a cooperating arcing contact releasably attached to the supporting means where it is normally fastened in a predetermined positionsaid cooperating arcing contact having one surface means for separably engaging said stationary arcing contact during movement of the supporting means from said closed position toward said open position until after said first terminal disengages said first main contact, and having another surface means adapted to engage the side of said first terminal nearest to the first main contact with the supporting means in said open position,

(ii) means adapted to maintain contact pressure between said other surface means of the cooperating arcing contact and said first terminal side when engaged thereby, and

spaced-apart main electric is provided for containing and extinguishing any arc drawn between the stationary arcing contact and the cooperating arcing contact of the holding means upon separation thereof during movement of the supporting means to its open position.

3. The switch of claim 1 in which the means for unfastening the arcing contact of the holding means comprises a threaded bolt attached to this contact and normally secured in a cooperating nut affixed to the supporting means.

4. The switch of claim 3 in which the contact-pressuremaintaining means comprises spring means adapted to urge the first terminal relative to the supporting means in a direction to hold it against said other surface means of the cooperating arcing contact. a

5. A switch comprising:

(a) first and second spaced-apart pairs of jaw-like main electric contacts;

(b) a relatively stationary pair of jaw-like arcing contacts connected to the first pair of main contacts and generally aligned therewith;

(0) means adapted removably to support a bridge-like electroconductive element having first and second blade-like terminals at opposite ends thereof, said means being movable between a closed positionin which the first and second terminals of the supported element are respectively inserted in said first and second pairs of main contactsand an open position in which said first terminal is separated from said first pair of main contacts,

(d) said supporting means including means adapted releasably to hold said first terminal, said holding means comprising (i) an inverted L-shape arcing contact having one end pivotally mounted on the supporting means and having its other end releasably fastened to the supporting means, the L-shape arcing contact when so fastened having one side disposed,

between said stationary arcing contacts during movement of the supportingmeans from said closed position toward said open position until after said first terminal separates from said first pair of main contacts and having its other side adapted to abut the edge of said first terminal that is nearest the first pair of main contacts after separation therefrom,

(ii) means adapted yieldably to maintain good electrical and physical contact between said first terminal edge and the abutting side of the 1 1i L-shape arcing contact, and

, (iii) means for unfastening said other end of the L-shape arcing contact which is then pivotable to a position releasing said first terminal and permitting removal of the supported element from the supporting means.

6. The switch of claim 5 in which the bridge-like electroconductive element comprises a cartridge fuse and in which the L-shape arcing contact is thinner than the first blade-like terminal of said fuse.

OTHER REFERENCES German printed application, 1,825,194, January 19, 1961.

BERNARD A. GILHEANY, Primary Examiner. 

1. A SWITCH COMPRISING: (A) FIRST AND SECOND SPACED-APART MAIN ELECTRIC CONTACTS; (B) A RELATIVELY STATIONARY ARCING CONTACT CONNECTED ELECTRICALLY TO THE FIRST MAIN CONTACT AND DISPOSED PHYSICALLY ADJACENT THERETO; AND (C) MEANS ADAPTED REMOVABLY TO SUPPORT A CARTRIDGE FUSE HAVING FIRST AND SECOND TERMINALS AT OPPOSITE ENDS THEREOF, SAID MEANS BEING MOVABLE BETWEEN A PREDETERMINED CLOSED POSITION-IN WHICH THE FIRST AND SECOND TERMINALS OF THE SUPPORTED FUSE RESPECTIVELY ENGAGE SAID FIRST AND SECOND MAIN CONTACTS-AND AN OPEN POSITION IN WHICH SAID FIRST TERMINAL AND SAID FIRST MAIN CONTACT ARE DISENGAGED; (D) SAID SUPPORTING MEANS INCLUDING MEANS ADAPTED TO HOLD THE FIRST TERMINAL OF SAID FUSE, SAID HOLDING MEANS COMPRISING (I) A COOPERATING ARCING CONTACT RELEASABLY ATTACHED TO THE SUPPORTING MEANS WHERE IT IS NORMALLY FASTENED IN A PREDETERMINED POSITIONSAID COOPERATING ARCING CONTACT HAVING ONE SURFACE MEANS FOR SEPARABLY ENGAGING SAID STATIONARY ARCING CONTACT DURING MOVEMENT OF THE SUPPORTING MEANS FROM SAID CLOSED POSITION TOWARD SAID OPEN POSITION UNTIL AFTER SAID FIRST TERMINAL DISENGAGES SAID FIRST MAIN CONTACT, AND HAVING ANOTHER SURFACE MEANS ADAPTED TO ENGAGE THE SIDE OF SAID FIRST TERMINAL NEAREST TO THE FIRST MAIN CONTACT WITH THE SUPPORTING MEANS IN SAID OPEN POSITION, (II) MEANS ADAPTED TO MAINTAIN CONTACT PRESSURE BETWEEN SAID OTHER SURFACE MEANS OF THE COOP- 